Fast and automated tool-changing device with standard conical tool support for digitally controlled bending machine

ABSTRACT

The invention concerns a digitally controlled machine for bending, forming, folding or coiling a bar, said machine comprising in standard manner a frame, a rotary bending tool to produce bends in different planes, wherein a bar is moved along an unwinding axis and brought through a bending shank borne by the frame then through the bending tool ( 3 ) whereof the digital axial movement, perpendicular to the unwinding axis is transmitted from a motor ( 5 ) by means of a lathe ( 2 ). The invention is characterised in that: the bending tool ( 3 ) is borne by a standard conical tool support ( 1 ); and the lathe is combined with means automatically unclamping the jaws ( 6 ) of the pliers when the lathe reaches the end of its digital axial stroke away from the bending station, and automatically clamping said jaws when the lathe begins its digital axial movement in the opposite direction, bringing it closer to the bending station.

[0001] The present invention relates to a tool-changing device for a numerically controlled machine for curving, forming, folding and bending bars or sections.

[0002] The main objective of the invention is to produce a fast and automated tool-changing device, something which does not exist in the prior art for this type of machine.

[0003] The device according to the invention may, in particular, but non-limitingly, apply to numerically controlled machines with retractable or resettable snouts as described in the applicant's patent application FR 00 04317.

[0004] The invention consists of a numerically controlled machine for curving, forming, folding or bending a bar, the machine comprising, in the conventional way, a bed and a rotary bending tool so as to be able to obtain folds in various planes, in which machine a bar is moved along a line of travel and passed through a folding snout carried by the bed then through the folding tool, the axial numerical movement of which, perpendicular to the line of travel, is transmitted from a motor by means of a turner, characterized in that:

[0005] on the one hand, the folding tool is carried by a standard conical tool support,

[0006] on the other hand, the turner is combined with automatic means of loosening the jaws of the gripper when the turner reaches the end of its numerical axial travel in the direction away from the folding station, and of automatically tightening said jaws when the turner begins the numerical axial movement in the opposite direction, in the direction toward the folding station.

[0007] According to a preferred but nonlimiting form of the invention, the function of automatically loosening and tightening the gripper is tied to the function of numerically moving the turner in an axial direction, these functions being performed by the same set of means.

[0008] The invention will be better understood with the aid of the following description of one nonlimiting embodiment of the invention, in conjunction with the following attached figures:

[0009]FIGS. 1 and 2: outline diagrams of one embodiment showing the tool support gripper in the tightened gripping position and the loosened release position, respectively.

[0010] To implement the invention, the applicant chose to use an assembly already in use on other machine tools and for machining applications, namely a standard assembly [conical tool holder (1) and gripper (2)].

[0011] According to the embodiment depicted in the figures, the tool holder (1) with its tool (3) can be secured (or released) by a gripper (2) to a transmission assembly known as a turner (4) transmitting the movements from the electric motor (5) of the numerically controlled machine.

[0012] Furthermore, the turner makes it possible in a known way to move the tool holder (1) in translation so as to move the tool away from the folding station or position it with respect thereto.

[0013] The invention consisted in causing the jaws (6) of the gripper (2) to be loosened automatically at the end of the translational movement of the turner (4), for example according to the embodiment of FIGS. 1 and 2.

[0014] In the tightened position of FIG. 1, the jaws (6) of the gripper (1) are compressed inside the narrow part of a conical stop (7), and grip the end of the tool holder (1).

[0015] A screw-nut system (8) for the axial positioning of the turner (4) drives the turner axially in the direction of the motor (5) in the direction of the arrow {right arrow over (F)}₁.

[0016] At the end of travel (see FIG. 2), the axle (9) of the screw-nut system comes into contact with the end of a rod (13) for the axial guidance of the gripper (2), within the turner, and drives said gripper (2) in an axial movement, relative to the turner, in the direction of the arrow {right arrow over (F)}₂, the opposite direction to {right arrow over (F)}₁.

[0017] The gripper moves closer to the conical stop and the jaws (6), under the effect of a spring situated in the gripper and unreferenced, part in the widened part of the conical stop (7), thus automatically releasing the end of the tool holder (1).

[0018] A device commonly used in machine tools used for machining, and not depicted, changes the assemblies [tool holder (1)-tool (3)] from an automated tool work.

[0019] Thus, the number of fold radii per item becomes limited only to the variety of tools in the rack.

[0020] The axial movement of the gripper (2), relative to the turner, in the direction of the arrow {right arrow over (F)}₂, has also had the effect of compressing a tension spring (10) between a moving stop (11) of the end of the axial guide rod (13) and a fixed stop (12) of the turner.

[0021] When the turner begins its return travel, in the opposite direction to the arrow {right arrow over (F)}₁, this spring will automatically move the gripper (2) away from its conical stop, causing automatic gripping of the tool holder by the jaws (6) of said gripper.

[0022] Then, when the spring (10) reaches it normal tension position defined by the length of the rod (13) for axial guidance of the gripper, the axle (9) of the screw-nut system separates from the end of the rod (13) and the gripper, in the remainder of its movement, exerts on the cone, or taper, a constant force determined by the spring (10).

[0023] In the embodiment which has just been described, the functions of automatically loosening and tightening the gripper are tied to the function of numerically moving the turner in an axial direction, these functions being performed by the same set of means.

[0024] It is possible to envisage other embodiments in which the functions of automatically tightening and loosening the gripper are separate from the numerical axial movement function, these two functions being performed by separate means.

[0025] The tightening and loosening means may, for example, be driven by hydraulic or pneumatic rams, possibly external to the turner. 

1. A numerically controlled machine for curving, forming, folding or bending a bar, the machine comprising, in the conventional way, a bed and a rotary bending tool so as to be able to obtain folds in various planes, in which machine a bar is moved along a line of travel and passed through a folding snout carried by the bed then through the folding tool (3), the axial numerical movement of which, perpendicular to the line of travel, is transmitted from a motor (5) by means of a turner (2), characterized in that: on the one hand, the folding tool (3) is carried by a standard conical tool support (1) on the other hand, the turner is combined with automatic means of loosening the jaws (6) of the gripper when the turner reaches the end of its numerical axial travel in the direction away from the folding station, and of automatically tightening said jaws when the turner begins the numerical axial movement in the opposite direction, in the direction toward the folding station.
 2. The machine as claimed in claim 1, characterized in that the function of automatically loosening and tightening the gripper is tied to the function of numerically moving the turner in an axial direction, these functions being performed by the same set of means.
 3. The machine as claimed in claim 2, characterized in that, in the tightened position, the jaws (6) of the gripper (1) are compressed by the narrow part of a conical stop (7) and grip the end of the tool holder (1), a screw-nut system (8) for the axial positioning of the turner (4) drives the turner axially in the direction of the motor (5) in the direction of an arrow {right arrow over (F)}₁, at the end of travel the axle (9) of the screw-nut system comes into contact with the end of a rod (13) for the axial guidance of the gripper (2), within the turner, and drives said gripper (2) in an axial movement, relative to the turner, in the direction of an arrow {right arrow over (F)}₂, the gripper moves closer to the conical stop and the jaws (6), under the effect of a tension spring situated in the gripper, part in the widened part of the conical stop (7), thus automatically releasing the end of the tool holder (1), the axial movement of the gripper (2), relative to the turner, in the direction of the arrow {right arrow over (F)}₂, has also had the effect of compressing a tension spring (10) between a moving stop (11) of the end of the axial guide rod (13) and a fixed stop (12) of the turner, as the turner returns, in the opposite direction to the arrow {right arrow over (F)}₁, this spring will automatically move the gripper (2) away from its conical stop, causing automatic gripping of the tool holder by the jaws (6) of said gripper, then, when the spring (10) reaches its normal tension position defined by the length of the rod (13) for axial guidance of the gripper, the axle (9) of the screw-nut system separates from the end of the rod (13) and the gripper, in the remainder of its movement, exerts on the cone, or taper, a constant force determined by the spring (10).
 4. The machine as claimed in claim 1, characterized in that the functions of automatically tightening and loosening the gripper are separate from the numerical axial movement function, these two functions being performed by separate means.
 5. The machine as claimed in claim 4, characterized in that the tightening and loosening means are driven by rams. 